This invention relates to metallization compositions, particularly those useful in heat-processed applications. Such compositions include, for example, those used in manufacture of multi-layer ceramic capacitors as body electrodes or electrode-connecting endterminations.
A great deal of work has been done in manufacturing of coating pastes compositions for immediate or eventual use in metallizing of ceramic surfaces. Among those more demanding applications are those encountered in the manufacture of multilayer ceramic capacitors which have thin electroconductive-metal body electrodes and end-terminations whereby a plurality of such electrodes are connected electrically into a single electrical terminal for appropriate connection into an electrical circuit. Such compositions are generally characterized by a reliance on the properties of expensive noble metal constituents.
It has been a general objective of much of the prior work to achieve electrodes having a superior combination of cost and performance. Often the work is directed to providing thin electrodes which are characterized by improved performance characteristics. Such systems are discussed in such references as U.S. Pat. No. 4,426,356 to Nair wherein up to about thirty percent of an inorganic powder is incorporated with finely-divided noble metal powders, into a metallizing paste for use in making capacitors. Numbers of other patents disclose the use of relatively inexpensive powders, particularly nickel powder, in combination with a noble metal in such pastes. See, for example, U.S. Pat. Nos. 3,872,360 and 3,988,651. Other patents which relate to the general area of interest include U.S. Pat. Nos. 4,055,850; 4,075,081 and 3,237,066; and 3,824,127. Still another attempt to improve electrode economics is described in U.S. Pat. No. 3,679,950 which discloses the use of a so-called "fugitive electrode process". Despite such work, it has continued to be a problem to optimize the performance and economics of such metallizing solutions. The chemical stability and/or electroconductive characteristics of the newer products tend to be so inferior to the conventionally-used noble metals that the resultant cost savings does not justify use of the newer products in many applications.